serial: st-asc: Fix SysRq char handling

This driver, like several others, uses the upper bits of the character
to track both real and dummy state. Unfortunately it neglects to mask
these bits properly when passing the character data around. This means
neither break detection nor sysrq character handling work correctly.

This patch adds the requires masking and has been tested to confirm
that it correctly handles magic sysrq sequences on ST's B2020 board.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index 21e6e84c0df8..dd3a96e07026 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -295,7 +295,7 @@ static void asc_receive_chars(struct uart_port *port)
                         status & ASC_STA_OE) {
 
                         if (c & ASC_RXBUF_FE) {
-                                if (c == ASC_RXBUF_FE) {
+                                if (c == (ASC_RXBUF_FE | ASC_RXBUF_DUMMY_RX)) {
                                         port->icount.brk++;
                                         if (uart_handle_break(port))
                                                 continue;
@@ -325,7 +325,7 @@ static void asc_receive_chars(struct uart_port *port)
                                 flag = TTY_FRAME;
                 }
 
-                if (uart_handle_sysrq_char(port, c))
+                if (uart_handle_sysrq_char(port, c & 0xff))
                         continue;
 
                 uart_insert_char(port, c, ASC_RXBUF_DUMMY_OE, c & 0xff, flag);